Three of the five soldiers killed were Muslim and two were Buddhist.
Ruso police, according to the newspaper, said they believed the roadside bomb attack was masterminded by Runda Kumpulan Kecil guerrillas.
Soldiers and police on Friday tried to hunt down fighters from the armed group who were suspected to have fled into the mountains.
The attack on Friday took place in neighbouring Yala province, where another roadside bomb killed three soldiers in a pickup truck.
Yala, together with Narathiwat and Pattani, has a predominantly Muslim population, many of whom have long complained of discrimination and marginalisation by the government in Bangkok, especially in the areas of education and job opportunities.
|Eight soldiers were killed in two roadside bombings over two days [Reuters]
Al Jazeera's Wayne Hay, reporting from Yala, said, as was usually the case, no one had claimed responsibility for the attacks.
But over the years, much of the violence has been blamed on Muslim insurgent groups believed to be fighting for an autonomous region encompassing the three southern provinces, our correspondent said.
Officials were also saying they believed organised crime groups were involved in the violence, he added.
More than 4,000 people have been killed in the southern-most provinces since the insurgency reignited in 2004.